U.S. patent number 4,623,478 [Application Number 06/836,940] was granted by the patent office on 1986-11-18 for composition and method for making foamed polyester resin.
This patent grant is currently assigned to U.S. Peroxygen Company. Invention is credited to Ronald L. Pastorino.
United States Patent |
4,623,478 |
Pastorino |
November 18, 1986 |
Composition and method for making foamed polyester resin
Abstract
A composition for foaming polyester which includes a carbonate
or bicarbonate salt and water intermixed with a finely divided
solid free flow agent such as synthetic amorphous silica. The free
flow agent is added in an amount sufficient to absorb all of the
water and render the composition a free flowing powder. The
composition is readily mixable with an unsaturated polyester resin
media. A source of acid in the mixture liberates gas from the
carbonate or bicarbonate, and good foam structures having small
uniform cells are obtained.
Inventors: |
Pastorino; Ronald L. (San
Anselmo, CA) |
Assignee: |
U.S. Peroxygen Company
(Richmond, CA)
|
Family
ID: |
27089534 |
Appl.
No.: |
06/836,940 |
Filed: |
March 6, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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623811 |
Jun 22, 1984 |
4600727 |
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Current U.S.
Class: |
516/11;
252/183.16; 521/138; 521/72; 521/91; 521/92 |
Current CPC
Class: |
C08J
9/08 (20130101); C08J 2367/06 (20130101) |
Current International
Class: |
C08J
9/00 (20060101); C08J 9/08 (20060101); C06D
005/10 () |
Field of
Search: |
;252/350,188.31
;521/72,91,92,138 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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652770 |
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May 1951 |
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GB |
|
2029834 |
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Mar 1980 |
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GB |
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Primary Examiner: Foelak; Morton
Attorney, Agent or Firm: Townsend & Townsend
Parent Case Text
This is a division of application Ser. No. 623,811 filed June 22,
1984, now U.S. Pat. No. 4,600,727.
Claims
What is claimed is:
1. A composition for use in foaming polyester resin at room
temperature consisting of: a salt selected from sodium and
potassium carbonates and bicarbonates; water; and intermixed
therewith sufficient finely divided solid free flow agent to absorb
said water and make the composition a free flowing powder.
2. A composition in accordance with claim 1, wherein said salt is
initially dissolved in said water before intermixture with said
free flow agent.
3. A composition in accordance with claim 2, wherein said salt is
dissolved in said water in an amount sufficient to saturate the
solution.
4. A composition in accordance with claim 3, wherein said salt is
initially dissolved in said water at elevated temperature.
5. A composition in accordance with claim 4, wherein said elevated
temperature is about 50.degree.-90.degree. C.
6. A composition in accordance with claim 4, wherein said elevated
temperature is about 60.degree.-70.degree. C.
7. A composition in accordance with claims 2, 3 or 4, wherein said
free flow agent is selected from natural and synthetic silicas and
silicates.
8. A composition in accordance with claim 1, wherein said salt is
potassium bicarbonate.
9. A composition in accordance with claim 1, wherein said salt and
water are separately intermixed in said composition.
Description
BACKGROUND OF THE INVENTION
This invention relates to the making of foams from unsaturated
polyester resins. More particularly, it relates to compositions
useful in methods for creating a foam structure in polyester resin
products by providing a source of gas for expansion of the
resin.
There is a well developed body of prior art designed to foam
unsaturated polyester resins with gaseous blowing agents. Over the
years unsaturated polyesters have been foamed by generating
CO.sub.2 gas through the acid decomposition of carbonate and
bicarbonate salts. Typicall.y the carbonate salt per se is mixed
directly into the unsaturated resin mass and acid added. Typical
references employing such techniques include U.S. Pat. Nos.
3,479,303, 4,016,112, 4,028,289, 4,119,583, 4,122,047, 4,347,331
and British Pat. No. 2,029,834.
To date there has been only limited commercial success utilizing
carbonate salts for generating CO.sub.2. One of the drawbacks which
apparently limits wide spread industry acceptance of the process
includes the requirement for a significant amount of acid such as
acetic acid and water to be added to the resin to help solubilize
the carbonate granules and to start their decomposition for gas
formation. In general, there has been a lack of consistent results
in terms of the desired uniform foam structures. This lack of
uniformity is most likely due to difficulties in dispersing a
relatively coarse inorganic salt in the organic medium presented by
the unsaturated polyester resin.
SUMMARY OF THE INVENTION
Foams from unsaturated polyester resin having a uniform and fine
cell structure are now consistently possible utilizing carbonate
and bicarbonate salts. This goal is accomplished by utilizing a
composition including a salt selected from sodium and potassium
carbonates and bicarbonates, or mixtures thereof, and water
intermixed with a sufficient amount of finely divided solid free
flow agent to absorb the water and render the composition a free
flowing powder. In the preferred embodiment the salt is initially
dissolved in the water before intermixture with the free flow
agent. The free flowing powder containing the inorganic salt is
readily mixable with, and uniformly dispersable in, the organic
resin media. The salt is present in the powder as relatively
uniform fine particles. While the composition is a free flowing
powder, water is present on the free flow agent to provide an
efficient reaction media between acid and the carbonate or
bicarbonate salt in the formation of CO.sub.2 gas. The free flow
agent can also act as a nucleating agent in the foaming
process.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present composition is used in a process in which liquid
unsaturated polyesters are converted to a foam structure. Polyester
resins useful in this invention are disclosed in detail in U.S.
Pat. No. 4,216,294, incorporated herein by reference. Typically,
the unsaturated polyester resin is preliminarily combined with an
accelerator or promoter, also as described in U.S. Pat. No.
4,216,294. Promoted unsaturated polyester resins are generally
contemplated for use in the present invention.
The unsaturated polyester is cured and crosslinked with an organic
peroxide initiator, preferably a ketone peroxide such as methyl
ethyl ketone peroxide. The organic peroxide will generally be
present in an amount of about 0.5-5 weight percent of resin, more
typically about 1-2 weight percent. The peroxide composition may
contain diluents so that the peroxide content of the composition
used may only be about 50% by weight. Amounts given here are based
on peroxide content of such compositions.
The present invention is consistent with the prior art in that
various additives may be included in the resin formulation to be
foamed. For example, silicone surfactants have been utilized to
insure entrapment and uniform dispersion of the gas liberated by
the blowing agent. Again, typical silicone surfactants are
disclosed in U.S. Pat. No. 4,216,294, incorporated herein by
reference, and may be used in the present process.
The novel composition used in the present invention includes one of
the highly water soluble sodium and potassium carbonates and
bicarbonates, or mixtures thereof. The selected salt is preferably
initially dissolved in water. In the preferred embodiment a
saturated solution is sought. Higher concentrations of saturated
solutions are obtained by utilizing an elevated temperature for the
water. Beneficially, the salt is added to water at about
50.degree.-90.degree. C., and for convenience, at a temperature of
about 60.degree.-70.degree. C.
The saturated liquid is then intermixed with a finely divided solid
free flow agent present in an amount to absorb all of the water and
thereby precipitate the dissolved salt. In doing so, the salt is
dispersed on the free flow agent in a finely divided uniform state.
In this form the salt and the water are most easily dispersed in
the organic polyester media.
In using the present compositions, sufficient composition is added
to provide about 1-10 weight percent of salt with respect to the
polyester resin. The amount of salt in the composition will depend
in part upon the concentration of salt in the water combined with
the free flow agent. Where a preferred preformed saturated aqueous
salt solution is used, the amount of salt in the composition will
depend upon the temperature of the water being saturated with the
salt. As will be seen, typical formulations will include
compositions in which the salt comprises about 26% by weight of the
composition which also contains water and free flow agent, and in
which the salt was dissolved to saturate water at about 60.degree.
C. In the preferred embodiment the composition is added to provide
about 3-6 weight percent of salt with respect to the polyester
resin. While higher concentrations can be used, there does not
appear to be any substantial benefit in density reduction, whereas
lower salt concentrations may not provide the same degree of
density reduction in the foamed resin product.
The free flow agent is selected from natural and synthetic silica
and silicates and is generally a hydrophilic finely divided solid
material capable of absorbing water and carrying precipitated
carbonate and bicarbonate salts thereon. Typical materials are
synthetic amorphous silica available under the trademark SIPERNAT
22 and utilized in the working examples herein. Other materials
which are suitable as a free flow agent are diatomaceous earth and
fumed silicas such as the commercial product known as AEROSIL 972.
Typical silicate materials are synthetic alkaline earth metal
silicates such as hydrous magnesium and calcium silicates. A
typical commercial material in this latter category is the calcium
silicate offered by Johns-Manville under the name MICRO-CEL.
While the invention is preferably practiced by dissolving the
carbonate salt in heated water and precipitating the salt out of
the solution onto the free flow agent while taking up the water on
the free flow agent, improvements in the foamed products can be
obtained by simply mixing the water, salt and free flow agent
concurrently or sequentially adding salt and water to the free flow
agent, instead of initially dissolving the salt in water and then
combining the free flow agent.
During the making of the foamed product a gas is liberated from the
carbonate or bicarbonate salt by reaction with a source of acid.
Separate acids may be added to the reaction mixture for this
purpose. Both inorganic and organic acids may be added for this
purpose and in amounts which may facilitate the rate and extent of
the foaming process beyond that obtained from any acid component
already present in the particular polyester resin being used. The
amounts utilized will generally be similar to the amounts of acid
utilized in prior art processes employing CO.sub.2 producing
blowing agents. In the present process it is generally found that
the polyester resin used in the process already contains sufficient
acidic component to react with the carbonate or bicarbonate salt.
Therefore, no additional acid will generally be required in the
present process.
The following will more specifically illustrate the invention.
EXPERIMENTAL
60 grams of KHCO.sub.3 was dissolved in 100 grams of water heated
to 58.degree.-60.degree. C. With slow mixing, the solution was
added to 70 grams SIPERNAT 22. The resulting powder was free
flowing. This product is designated "D mix".
To 50 grams of CARGILL PE 8245 promoted unsaturated polyester resin
was added 0.50 grams of Union Carbide's L5340 silicone surfactant,
10 grams "D mix," and 1.5 grams of Esperfoam FR ketone peroxide
solution. This was hand mixed for approximately 45 seconds in an 8
ounce polyester jar.
Within 3 minutes there was about a two-fold increase in resin
volume. At about 14 minutes the rise reached a maximum. Curing was
evident at approximately 23 minutes and at 31 minutes the foamed
resin was removed from the jar. The foam was uniform with a
relatively fine cell structure.
The resultant density was 0.278 grams/cc or 17.4 lbs/ft.sup.3.
Utilizing the above general procedure the data shown below in Table
I was obtained. Trial #2 represents a control run where no blowing
agent was used and no density reduction afforded. Other trials as
indicated did not predissolve the salt in water. These are
designated "hand mix".
TABLE I
__________________________________________________________________________
Room Temperature 68-73.degree. F.
__________________________________________________________________________
Trial #: 1 2 3 4 5 6 7 8 9 10
__________________________________________________________________________
resin PE 8245 50 50 50 50 50 50 50 50 50 50 wt resin L5340 0.25
0.25 0.28 0.25 0.25 0.50 0.50 0.50 0.10 "A mix".sup.1 g 26.8 "D
mix".sup.2 g 2.6 3.1 5.0 8.0 10.0 10.0 6.0 10.0 "F mix".sup.3 g
NaHCO.sub.3 g KHCO.sub.3 g H.sub.2 O g Sipernat 22 g Esperfoam FR g
1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Quickset 90 g Quickset Super g
1.5 Demold time 60' 120' 67' 38' 26' 29' 31' 29' 20' 36' (.about.
min.) Density/ g/cc 0.58 1.15 0.57 0.51 0.41 0.33 0.28 0.35 0.34
0.32 lbs/ft.sup.3 36.2 71.8 35.6 32.1 25.2 20.3 17.4 22.0 21.3 20.2
Rating of fair no fair good good good good good good good Cell
structure: foam to Extent of good Small Uniform Cells
__________________________________________________________________________
Trial #: 11 12 13 14 15 16 17 18 19 20
__________________________________________________________________________
resin PE 8245 50 50 50 50 50 50 50 50 50 50 wt resin L5340 0 0.25
0.25 0.25 0.25 0.25 0.25 0.30 0.30 0.30 "A mix".sup.1 g "D
mix".sup.2 g 10.0 4 4.1 0 5.0 9.0 "F mix".sup.3 g 8.0 3.0
NaHCO.sub.3 g 1.8 KHCO.sub.3 g 2.7 1.8.sup.4 H.sub.2 O g 3.0 3.0
Sipernat 22 g 2.2 Esperfoam FR g 1.5 1.5 2.0 1.5 1.0 1.5 1.5 1.5
1.5 Quickset 90 g 1.5 Quickset Super g Demold time 23' 36' 24' 44'
29' 54' 32' 24' 30' 25' (.about. min.) Density/ g/cc 0.46 0.45 0.43
0.94 0.43 0.43 0.54 0.43 0.30 0.47 lbs/ft.sup.3 28.8 28.4 26.9 58.9
26.9 26.9 33.4 26.9 19.0 29.6 Rating of poor good fair poor good
poor fair good good good Cell structure: (split) to to Extent of
good poor Small Uniform Cells
__________________________________________________________________________
.sup.1 A mix = hand mix of 86.7% KHCO.sub.3, 6.9% Aerosil R972 +
6.4% L5340 .sup.2 D mix = 26.0% KHCO.sub.3, 43.1% H.sub.2 O, 30.9%
Sipernat 22 .sup.3 F mix = 24.8% KHCO.sub.3, 4.9% NaHCO.sub.3,
41.3% H.sub.2 O, 28.9% Sipernat 22 .sup.4 hand mixed "D mix" at
room temperature
FIG. 1 graphically represents some of the data obtained with
particular reference to using various concentrations of "D mix".
Also included in the graph are points obtained when using 2.0 and
4.0 pphr (parts per hundred based on the resin) of Esperfoam FR
showing that peroxide concentration changes does not produce
significantly different results. Use of different peroxide
compositions (Quickset 90 and Quickset Super) resulted in somewhat
higher densities. (These are all ketone peroxide formulations
available from U.S. Peroxygen Company, Richmond, Calif.)
The following examples illustrate the use of different polyester
resins.
Ex. I Resin
U.S. Steel MR-643 (Cultured Marble resin)
100 parts MR-643
1.1 parts L5340 silicone surfactant
20.0 parts "C mix".sup.1)
3.0 parts Esperfoam FR (MEKP)
Demold time: 27'
Density: 0.335 g/cc (20.9 lbs/ft.sup.3)
Appearance of foam cell structure: fair to good
Ex. II Resin
U.S. Steel MR-12184 ("Laminating resin, 50% maleic")
100 parts MR-12184
0.9 parts L5340
28 parts "C mix".sup.1)
3.0 Esperfoam FR
Demold time: 23'
Density: 0.445 g/cc (27.8 lbs/ft.sup.3)
Appearance of foam cell structure: fair to good
Ex. III Resin
Ashland Chemical Aropol 8821
100 parts Aropol 8821 Casing Resin
0.71 parts L5340
17.6 parts "H mix".sup.2)
0.23 parts Esperfoam FR
2.7 parts benzoyl peroxide 40% suspension (BZQ-40)
Demold time: 60'
Density: 0.25 g/cc (15.5 lbs/ft.sup.3)
Appearance of foam cell structure: fair to good
Ex. IV Resin
Ashland Chemical Aropol 8821
100 parts Aropol 8821
0.71 parts L5340
17.6 parts "H mix".sup.2)
0.53 parts Hi-Point 90 (MEK Peroxide)
Demold time: 55'
Density: 0.25 g/cc (15.5 lbs/ft.sup.3)
Appearance of foam cell structure: fair to good
Ex. V Resin
Ashland Chemical Aropol 8821
100 parts Aropol 8821
0.71 parts L5340
17.6 parts "Room temp H mix".sup.3)
0.53 parts Hi-Point 90
Demold time: 67'
Density: 0.268 g/cc (16.7 lbs/ft.sup.3)
Appearance of foam cell structure: poor to fair
Ex. VI Resin
Freeman Chemical Stypol 40-4069 (G.P. spray-up resin)
______________________________________ Trial: 1 2 3 4 5 6 7 8
______________________________________ resin (g): 50 50 50 50 50 50
50 50 L5340 (g) -- -- -- -- -- -- -- -- "J mix" 10 10 10 10 10 --
10 5.1 (g).sup.4 KHCO.sub.3 (g) 10g glacial Acetic 0.25 0.50 0.75
1.25 0.50 0.50 acid (g) proprionic 0.75 acid (g) Esperfoam FR 0.75
1.0 1.0 1.0 1.0 0.75 Quickset 1.0 1.0 Extra Demold time 20' 13' 18'
18' 37' 16' 20' 18' (.about. min) Density: g/cc: 0.578 0.428 0.299
0.215 0.181 1.14 0.258 0.346 lb/ft.sup.3 : 36.1 26.7 18.7 13.4 11.3
71.1 16.1 21.6 Cell good good good good good no good good Structure
foam ______________________________________ .sup.1 "C mix": 23%
KHCO.sub.3, 43% H.sub.2 O, 34% Sipernat 22. Prepared by dissolving
KHCO.sub.3 in H.sub.2 O at approxi- mately 65.degree. C. and then
added to Sipernat. .sup.2 "H mix": 23.1% KHCO.sub.3, 11.5% K.sub.2
CO.sub.3, 38.5% H.sub.2 O, 26.9% Sipernat 22. Prepared by
dissolving the KHCO.sub.3 + K.sub.2 CO.sub.3 in H.sub.2 O at
approximately 65.degree. C. and adding to the Sipernat 22. .sup.3
"Room temp. H mix": A physical mixture of the "H mix" components
made by adding each to the Sipernat 22 and mixing at room temp.
.sup.4 "J mix": Prepared by dissolving KHCO.sub.3 in H.sub.2 O at
approximately 60.degree. C. and added to mixture of Kenite, L5340
and Sipernat 22. KHCO.sub.3 25.1% H.sub.2 O 42.0% Kenite 6.3%
(diatomaceous earth) L5340 3.5% Sipernat 22 23.0%
* * * * *